Done with the cardigan! Cotton thread #10, hook 2 mm. All charts are for size medium (American - 12, for breast 92 cm).
Crochet in a loop up to the row marked with oval, then start shaping armhole. Notice, I put chain stitches (ch) from some point to make sleeve wider. There is tc between them. Normally it's just tr (treble crochet) to the top of down square.